See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
! Missing $ inserted.
<inserted text>
$
l.16 ...<91>i<9a><db>v<e1>6<e8><e5>^^_^^G^^W[<db>o}<e4>^^?<91>a^^X<db><de>߅<ce><ec><a5>^^Q^
<99>J<a5><d2><e9>4<c6><fd><f0><e1>ý{<f7><d2><e9><f4><fd><fb><f7>߾}<fb><fe><fd>...
! Undefined control sequence.
l.16 ...*<85><89>x<fa><f4>i0<df>^^[^^?Accc<bf>~<fd><fa><9b>^^Q^^N<fb>E<ff>mT<f7>{<95>K<a7>\<bc>
ڇ^^O^^_<ee><de>bhh<e8>ӧO<ae><eb>j<9a>f<db>v<b1>X...
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
! You can't use `\eqno' in math mode.
\endmathdisplay@a ...\df@tag \@empty \else \veqno